It is often necessary to remove more than one component from a gaseous stream so as to clean the gaseous stream, recover one or more of the components, or both. Examples of such situations include the upgrading of natural gas, the purification of natural gas before liquefaction, removal of contaminants from air for breathing, and removal of high boiling components from air before cryogenic air separation. A widely used method to carry out such component removal is to contact the gaseous stream with adsorbent to transfer components from the gaseous stream to the adsorbent. Generally the adsorbent is in a fixed or moving bed.
There are essentially two types of processes known to the art to carry out such a multicomponent adsorption. In the first such type, the gaseous stream is passed through one mass of adsorbent and all of the components are adsorbed by the single adsorbent mass. Such a process has the advantage of low capital costs because only a single adsorbent bed and desorption scheme is necessary. However because the adsorbent equilibrium loading is reduced, such a process requires a relatively large amount of adsorbent to remove effectively all of the components. In addition, desorption energy requirements are quite high. In the second such type of multicomponent adsorption process, the gaseous stream is passed through more than one mass of adsorbent and each component is substantially completely removed from the gaseous stream in a distinct adsorbent mass. Adsorbent requirement is reduced in such a system because the more strongly sorbed component does not interfere with the removal of the less strongly sorbed component. However, desorption energy requirements for such a system are relatively high.
It is therefore an object of this invention to provide an improved process for the removal by adsorption of more than one component from a gaseous stream.
It is a further object of this invention to provide an improved process for the removal by adsorption of more than one component from a gaseous stream which is more energy efficient than heretofore known processes.